1. Field of the Invention
This invention relates generally to surface bonding on an indefinite or running length of flexible web and means for applying a separate web to a shaped web and more particularly to a corrugated web single-facer machine having self-adjusting web guides for holding a corrugated medium web against a corrugator roll in the single-facer.
2. Description of the Prior Art
The prior application, of which this is a continuation-in-part, has set forth the state of the art relating to web guides for the corrugated medium web in a single-facer machine. The invention of the prior application largely overcame the shortcomings and disadvantages of prior art machines; however, the present invention generally seeks to simplify and improve the effectiveness of the earlier invention. In particular, an object of the present invention is to eliminate the need for a separate fluid supply for expanding the elastic tube used to urge the guide members against the corrugated medium web, to eliminate the mounting of the guide structure for movement with the adhesive applying structure and yet maintain alignment of the guides with the adhesive applicator roll, and provide a means for applying greater or lesser pressure to all the guides simultaneously. This invention also embraces the method of applying yieldable preselectable pressure to the corrugate medium web at selected lateral locations along its width.
It is also an object of this invention to provide a method and apparatus superior to fixed types of web guides such as illustrated in U.S. Pat. Nos. 2,979,112; 3,220,911; and 3,366,527. Web guides such as shown in these patents are rigidly mounted and require individual adjustment to maintain the medium web in contact with the lower corrugating roll. In addition, they are subject to bending and breakage from splices and other irregularities in the paper stock and usually require readjustment as they become worn.
It is an additional object of this invention to provide a method and apparatus superior to non-fixed types of web guides such as illustrated in U.S. Pat. Nos. 3,630,806 and 3,951,725. For example, U.S. Pat. No. 3,630,806 shows a web guide pivoted on its end nearest the entrance of the corrugate medium between the guide and the lower corrugating roller; the opposite end of the guide is urged by spring pressure against the corrugated medium to press the medium against the lower corrugator roll. This arrangement is semi-rigid because of the pivot point 22a and does not allow for extra thickness of paper passing between the guide and its associated lower corrugating roll. In addition, some sort of readjustment would be needed to compensate for wear of the guides. The present invention overcomes such problems as will be hereinafter explained.
U.S. Pat. No. 3,951,725 shows a two-piece hinged web guide pivotably supportedfrom a fixed support; the two segments of the guide are independently urged by spring pressure against the lower corrugator roll. However, it should be noted that the segments are fixed to their supports and perfect alignment of the segments on the supports is necessary to achieve continuous contact of the segments against the corrugated medium web. It can also be seen that movement of the guide segments is limited by the hinge arrangement 77 joining the segments together, particularly in the embodiment of FIG. 4 and as pointed out in the specification in column 5, lines 18-27. Accordingly, it is an object of the present invention to provide a method and structure overcoming such disadvantages and, particularly, to provide a single-piece guide structure capable of great freedom of movement to compensate for irregularities in the corrugated medium web and requiring no readjustment to compensate for ordinary wear of the web guides as will be hereinafter explained.